Luminaires using waveguide bodies and optical elements

ABSTRACT

According to one aspect, a waveguide comprises a waveguide body having a coupling cavity defined by a coupling feature disposed within the waveguide body. A plug member comprises a first portion disposed in the coupling cavity and an outer surface substantially conforming to the coupling feature and a second portion extending from the first portion into the coupling cavity. The second portion includes a reflective surface adapted to direct light in the coupling cavity into the waveguide body.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application comprises a continuation of U.S. patentapplication Ser. No. 16/429,491; filed Jun. 3, 2019 (now U.S. Pat. No.10,808,891); which is a division of U.S. patent application Ser. No.15/812,729, filed Nov. 14, 2017 (now U.S. Pat. No. 10,344,922), which isa continuation of U.S. patent application Ser. No. 14/101,147, filedDec. 9, 2013 (now U.S. Pat. No. 9,869,432), which in turn claims thebenefit of U.S. Provisional Patent Application No. 61/758,660, filedJan. 30, 2013 U.S. patent application Ser. No. 14/101,147 furthercomprises a continuation-in-part of U.S. patent application Ser. No.13/842,521, filed Mar. 15, 2013 (now U.S. Pat. No. 9,519,095), andfurther comprises a continuation-in-part of U.S. patent application Ser.No. 13/839,949, filed Mar. 15, 2013 (now U.S. Pat. No. 9,581,751), andfurther comprises a continuation-in-part of U.S. patent application Ser.No. 13/841,074, filed Mar. 15, 2013 (now U.S. Pat. No. 9,625,638), andfurther comprises a continuation-in-part of U.S. patent application Ser.No. 13/840,563, filed Mar. 15, 2013 (now U.S. Pat. No. 10,436,969), andfurther comprises a continuation-in-part of U.S. patent Ser. No.13/938,877, filed Jul. 10, 2013 (now U.S. Pat. No. 9,389,367), all ownedby the assignee of the present application, and the disclosures of whichare incorporated by reference herein.

This patent application also incorporates by reference U.S. patentapplication Ser. No. 14/101,086, filed Dec. 9, 2013 (now U.S. Pat. No.9,690,029), U.S. patent application Ser. No. 14/101,099, filed Dec. 9,2013 (now U.S. Pat. No. 9,411,086), U.S. patent application Ser. No.14/101,132, filed Dec. 9, 2013 (now U.S. Pat. No. 9,442,243), U.S.patent application Ser. No. 14/101,129, filed Dec. 9, 2013 (now U.S.Pat. No. 10,234,616) and U.S. patent application Ser. No. 14/101,051,filed Dec. 9, 2013 (now U.S. Pat. No. 9,366,396).

REFERENCE REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable

SEQUENTIAL LISTING

Not applicable

FIELD OF THE INVENTION

The present inventive subject matter relates to optical waveguides, andmore particularly to optical waveguides for general lighting.

BACKGROUND OF THE INVENTION

An optical waveguide mixes and directs light emitted by one or morelight sources, such as one or more light emitting diodes (LEDs). Atypical optical waveguide includes three main components: one or morecoupling elements, one or more distribution elements, and one or moreextraction elements. The coupling component(s) direct light into thedistribution element(s), and condition the light to interact with thesubsequent components. The one or more distribution elements control howlight flows through the waveguide and is dependent on the waveguidegeometry and material. The extraction element(s) determine how light isremoved by controlling where and in what direction the light exits thewaveguide.

When designing a coupling optic, the primary considerations are:maximizing the efficiency of light transfer from the source into thewaveguide; controlling the location of light injected into thewaveguide; and controlling the angular distribution of the light in thecoupling optic. One way of controlling the spatial and angular spread ofinjected light is by fitting each source with a dedicated lens. Theselenses can be disposed with an air gap between the lens and the couplingoptic, or may be manufactured from the same piece of material thatdefines the waveguide's distribution element(s). Discrete couplingoptics allow numerous advantages such as higher efficiency coupling,controlled overlap of light flux from the sources, and angular controlof how the injected light interacts with the remaining elements of thewaveguide. Discrete coupling optics use refraction, total internalreflection, and surface or volume scattering to control the distributionof light injected into the waveguide.

After light has been coupled into the waveguide, it must be guided andconditioned to the locations of extraction. The simplest example is afiber-optic cable, which is designed to transport light from one end ofthe cable to another with minimal loss in between. To achieve this,fiber optic cables are only gradually curved and sharp bends in thewaveguide are avoided. In accordance with well-known principles of totalinternal reflectance light traveling through a waveguide is reflectedback into the waveguide from an outer surface thereof, provided that theincident light does not exceed a critical angle with respect to thesurface.

In order for an extraction element to remove light from the waveguide,the light must first contact the feature comprising the element. Byappropriately shaping the waveguide surfaces, one can control the flowof light across the extraction feature(s). Specifically, selecting thespacing, shape, and other characteristic(s) of the extraction featuresaffects the appearance of the waveguide, its resulting distribution, andefficiency.

Hulse U.S. Pat. No. 5,812,714 discloses a waveguide bend elementconfigured to change a direction of travel of light from a firstdirection to a second direction. The waveguide bend element includes acollector element that collects light emitted from a light source anddirects the light into an input face of the waveguide bend element.Light entering the bend element is reflected internally along an outersurface and exits the element at an output face. The outer surfacecomprises beveled angular surfaces or a curved surface oriented suchthat most of the light entering the bend element is internally reflecteduntil the light reaches the output face.

Parker et al. U.S. Pat. No. 5,613,751 discloses a light emitting panelassembly that comprises a transparent light emitting panel having alight input surface, a light transition area, and one or more lightsources. Light sources are preferably embedded or bonded in the lighttransition area to eliminate any air gaps, thus reducing light loss andmaximizing the emitted light. The light transition area may includereflective and/or refractive surfaces around and behind each lightsource to reflect and/or refract and focus the light more efficientlythrough the light transition area into the light input surface of thelight emitting panel. A pattern of light extracting deformities, or anychange in the shape or geometry of the panel surface, and/or coatingthat causes a portion of the light to be emitted, may be provided on oneor both sides of the panel members. A variable pattern of deformitiesmay break up the light rays such that the internal angle of reflectionof a portion of the light rays will be great enough to cause the lightrays either to be emitted out of the panel or reflected back through thepanel and emitted out of the other side.

Shipman, U.S. Pat. No. 3,532,871 discloses a combination running lightreflector having two light sources, each of which, when illuminated,develops light that is directed onto a polished surface of a projection.The light is reflected onto a cone-shaped reflector. The light istransversely reflected into a main body and impinges on prisms thatdirect the light out of the main body.

Simon U.S. Pat. No. 5,897,201 discloses various embodiments ofarchitectural lighting that is distributed from contained radiallycollimated light. A quasi-point source develops light that is collimatedin a radially outward direction and exit means of distribution opticsdirect the collimated light out of the optics.

Kelly et al. U.S. Pat. No. 8,430,548 discloses light fixtures that use avariety of light sources, such as an incandescent bulb, a fluorescenttube and multiple LEDs. A volumetric diffuser controls the spatialluminance uniformity and angular spread of light from the light fixture.The volumetric diffuser includes one or more regions of volumetric lightscattering particles. The volumetric diffuser may be used in conjunctionwith a waveguide to extract light.

Dau et al U.S. Pat. No. 8,506,112 discloses illumination devices havingmultiple light emitting elements, such as LEDs disposed in a row. Acollimating optical element receives light developed by the LEDs and alight guide directs the collimated light from the optical element to anoptical extractor, which extracts the light.

A.L.P. Lighting Components, Inc. of Niles, Ill., manufactures awaveguide having a wedge shape with a thick end, a narrow end, and twomain faces therebetween. Pyramid-shaped extraction features are formedon both main faces. The wedge waveguide is used as an exit sign suchthat the thick end of the sign is positioned adjacent a ceiling and thenarrow end extends downwardly. Light enters the waveguide at the thickend and is directed down and away from the waveguide by thepyramid-shaped extraction features.

Low-profile LED-based luminaires have recently been developed (e.g.,General Electric's ET series panel troffers) that utilize a string ofLED elements directed into the edge of a waveguiding element (an“edge-lit” approach). However, such luminaires typically suffer from lowefficiency due to losses inherent in coupling light emitted from apredominantly Lambertian emitting source such as a LED element into thenarrow edge of a waveguide plane.

SUMMARY OF THE INVENTION

According to one aspect, a waveguide comprises a waveguide body having acoupling cavity defined by a coupling feature disposed within thewaveguide body. A plug member comprises a first portion disposed in thecoupling cavity and an outer surface substantially conforming to thecoupling feature and a second portion extending from the first portioninto the coupling cavity. The second portion includes a reflectivesurface adapted to direct light in the coupling cavity into thewaveguide body.

According to another aspect, a luminaire, comprises a waveguide bodyhaving a lateral extent defined by a first face and a second faceopposite the first face. A coupling cavity extends in a depth dimensionof the waveguide body transverse to the lateral extent and is defined bya plurality of light coupling features that extend between the first andsecond faces. At least one of the light coupling features has a firstportion that extends laterally into the waveguide body to an extentgreater than an extent to which a second portion of the at least onelight coupling feature extends laterally into the waveguide body. Aplurality of LED's is disposed in the coupling cavity.

According to yet another aspect, a luminaire comprises a waveguide bodyhaving an interior coupling cavity extending into a portion of thewaveguide body remote from an edge thereof. An LED element extends intothe interior coupling cavity and comprises first and second sets of LEDswherein each LED of the first set comprises a first color LED and eachLED of the second set comprises a second color LED. The second colorLEDs are disposed between the first color LEDs and the first color LEDshave a first height and the second color LEDs have a second height lessthan the first height. The LED element further includes a lens disposedover the first and second sets of LEDs.

According to further aspect, a luminaire comprises a waveguide bodyhaving and interior coupling cavity, and an LED element extending intothe interior coupling cavity. The interior coupling cavity extends intoa portion of the waveguide body from an edge thereof and includes atleast one scalloped surface.

Other aspects and advantages of the present invention will becomeapparent upon consideration of the following detailed description andthe attached drawings wherein like numerals designate like structuresthroughout the specification.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an isometric view of a first embodiment of a luminaireincorporating one or more waveguides;

FIG. 1A is an isometric view of a second embodiment of a luminaireincorporating one or more waveguides;

FIG. 2 is a sectional view taken generally along the lines 2-2 of FIG. 1;

FIGS. 3A, 3B, and 3C are fragmentary, enlarged, isometric views of thefirst embodiment of FIG. 1 illustrating various extraction features;

FIG. 4 is an enlarged, isometric view of the plug member of FIG. 1 ;

FIG. 5 is an elevational view of the LED element used in the luminaireof FIG. 1 ;

FIG. 6 is an elevational view of the LED element disposed in a firstalternative coupling cavity that may be incorporated in the luminaire ofFIG. 1 ;

FIG. 7 is an enlarged, isometric view of a first alternative plug memberthat may be used in the coupling cavity of FIG. 6 ;

FIG. 8 is an elevational view of the LED element disposed in a secondalternative coupling cavity that may be incorporated in the luminaire ofFIG. 1 ;

FIG. 9 is an enlarged, isometric view of a second alternative plugmember that may be used in the coupling cavity of FIG. 8 ;

FIG. 10 is an elevational view of the LED element disposed in a thirdalternative coupling cavity that may be incorporated in the luminaire ofFIG. 1 ;

FIG. 11 is an elevational view of the LED element disposed in a fourthalternative coupling cavity that may be incorporated in the luminaire ofFIG. 1 ;

FIG. 12 is an enlarged, isometric view of a third alternative plugmember that may be used in the coupling cavities of FIGS. 11 and 13 ;

FIG. 13 is an elevational view of the LED element disposed in a fifthalternative coupling cavity that may be incorporated in the luminaire ofFIG. 1 ;

FIG. 14 is an elevational view of the LED element disposed in a sixthalternative coupling cavity that may be incorporated in the luminaire ofFIG. 1 ;

FIG. 15 is an elevational view of the LED element disposed in a seventhalternative coupling cavity that may be incorporated in the luminaire ofFIG. 1 ;

FIG. 16 is a fragmentary, enlarged, elevational view of a portion of theLED element disposed in the seventh alternative coupling cavity of FIG.15 ;

FIG. 16A is an elevational view of an eighth alternative coupling cavitythat may be incorporated in the luminaire of FIG. 1 ;

FIGS. 17 and 18 are elevational views of first and second alternativeLED elements that may be used in any of the luminaires disclosed herein;

FIG. 18A is an elevational view of yet another alternative LED elementthat may be used in any of the luminaires disclosed herein;

FIGS. 19 and 20 are isometric and elevational views, respectively, ofthe luminaire of FIG. 1 utilizing a masking element;

FIG. 21 is an isometric view of a waveguide having redirection features;

FIG. 22 is an enlarged, fragmentary, isometric view of the redirectionfeatures of the waveguide of FIG. 21 ;

FIG. 23 is an enlarged, isometric view of the waveguide of FIG. 21 witha portion broken away;

FIG. 24 is an isometric view of a waveguide having first alternativeredirection features;

FIG. 25 is a sectional view of the waveguide having first alternativeredirection features taken generally along the lines 25-25 of FIG. 24 ;

FIG. 26 is an elevational view of the waveguide having first alternativeredirection features during fabrication;

FIG. 27 is an elevational view of a waveguide having second and thirdalternative redirection features;

FIG. 28 is a diagrammatic fragmentary side elevational view of a furtherembodiment;

FIG. 28A is a diagrammatic plan view of the embodiment of FIG. 28 ;

FIG. 29 is an isometric view of a waveguide according to yet anotherembodiment;

FIG. 30 is a sectional view taken generally along the lines 30-30 ofFIG. 29 ;

FIG. 31 is a fragmentary sectional view according to still anotherembodiment;

FIG. 32 is a side elevational view of an LED element including a lens;

FIG. 33 is a plan view of a further alternative coupling cavity;

FIG. 34 is a plan view of yet another alternative coupling cavity; and

FIG. 35 is a sectional view taken generally along the lines 35-35 ofFIG. 33 .

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Some of the devices described herein utilize a “back-lit” approach inwhich one or more LED element(s) are located at least partially withinone or more coupling cavities each in the form of a hole or depressionin a waveguide body. In the embodiment shown in the figures, thecoupling cavity extends fully through the waveguide body, although thecoupling cavity may extend only partially through the waveguide body. Aplug member disposed at least partially in the coupling cavity or formedintegrally with the waveguide body to define the coupling cavity divertslight into the waveguide body. Light extraction features may be disposedin or on one or more surfaces of the waveguide body. A diffuser may bedisposed adjacent the waveguide body proximate the plug member(s). Insuch an arrangement, light emitted by the LED element(s) is efficientlycoupled into the waveguide body with a minimum number of bounces off ofpotentially absorbing surfaces, thus yielding high overall systemefficiency. This arrangement also offers additional potential benefitsin that multiple LED elements may be placed apart at greater distances,thereby reducing the need for costly and bulky heat sinking elements.Further, this approach is scalable in that the distance that light musttravel through the waveguide body may be effectively constant as theluminaire size increases.

In the back-lit approach described in the immediately precedingparagraph, it is desirable that the proper amount of light istransmitted through each plug member such that the local region on thediffuser aligned with the plug member shows neither a bright nor a darkspot, nor a spot with a color that differs noticeably from thesurrounding regions. Because the volume of the plug member is generallysmall, it is necessary to provide the plug member with a high degree ofopacity, which can be achieved by incorporating highly scatteringparticles that are typically small in diameter in the material of theplug member. However, small particle diameter typically leads topreferential scattering of short wavelength (blue) light. As a result,the light transmitted through the plug member may have a noticeableyellowish tint, which is typically undesirable.

Further, there exist practical limits on the amount of scatteringmaterial that may be incorporated into the plug member. As a result, itmay not be possible to achieve sufficient opacity without highabsorption using scattering particles that are incorporated into theplug member material. Finally, in regions where the plug member is incontact with the sidewall of the coupling cavity, the index ofrefraction difference interface at the surface of the cavity may beinterrupted, thereby allowing light to transmit from the plug memberinto the waveguide but not subject to refraction necessary to ensuretotal TIR within the waveguide.

Still further, a number of LEDs of the same color together comprising anLED element may be disposed in one or more of the coupling cavities.Alternatively, a number of LEDs not all of the same color and togethercomprising a multi-color LED element may be used in one or more of thecoupling cavities of the luminaire in order to achieve a desiredlighting effect, such as a particular color temperature. In the formercase, a non-uniform intensity of light may be produced. In the lattercase, a multi-color LED element may be subject to non-uniform colordistribution at high angles, leading to non-uniformity in the color andintensity of output luminance. A non-uniform color distribution also mayresult from a multi-color LED element having different color LEDs withvarying heights. For example, a multi-color LED element may include oneor more red LEDs surrounded by a plurality of blue-shifted yellow LEDs.Each red LED has a height that is less than a height of the surroundingblue-shifted yellow LEDs. The light emitted from the red LED, therefore,is obstructed at least in part by the blue-shifted yellow LED, such thatthe light emanating from the LED element is not uniform. In addition toheight differences, differences in the nature of the red andblue-shifted yellow LEDs affect the way the light is emitted from therespective LED.

According to an aspect of the present invention, the coupling cavitiesmay have any of a number of geometries defined by surfaces that promoteredirection of the light rays (e.g., through refraction) to better mixthe light rays developed by the LEDs. Other design features aredisclosed herein according to other aspects that promote light mixingand/or color and/or light intensity uniformity. Thus, for example, someembodiments comprehend the use of a thin reflective layer, such as ametal layer, on a portion of each plug member wherein the layer is ofappropriate thickness to allow sufficient light to transmit withoutsubstantial shift in color.

Other embodiments relate to the fabrication and surface smoothness ofthe surface(s) defining the cavity or cavities, change in LED positionand/or other modifications to the LED(s) or LED element(s), use ofinternal TIR features inside the waveguide body, and/or use of one ormore masking elements to modify luminance over the surface of theluminaire module.

Specifically, FIGS. 1 and 2 illustrate a low profile luminaire 30utilizing one or more back-lit waveguide luminaire portions 32 a-32 d tospread light uniformly. Each waveguide luminaire portion 32 a-32 d isjoined or secured to other portions 32 by any suitable means, such as aframe 34 including outer frame members 36 a-36 d and inner frame members36 e-36 g that are secured to one another in any suitable manner. One ormore of the frame members may be coated with a reflective white orspecular coating or other material, such as paper or a scattering film,on surfaces thereof that abut the portions 32. Alternatively, theluminaire portions 32 may abut one another directly, or may be separatedfrom one another by an air gap, an optical index matching coupling gel,or the like. In these latter embodiments, the luminaire portions 32 maybe secured together by any suitable apparatus that may extend around allof the portions 32 and/or some or all of the individual portions 32. Inany event, the luminaire 30 may comprise a troffer sized to fit within arecess in a dropped ceiling, or may have a different size and may besuspended from a ceiling, either alone or in a fixture or otherstructure. The luminaire 30 is modular in the sense that any number ofluminaire portions 32 may be joined to one another and used together.Also, the size of each luminaire portion 32 may be selected so that theluminaire portions may all be of a small size (e.g., about 6 in by 6 inor smaller), a medium size (e.g., about 1 ft by 1 ft), or a large size(e.g., about 2 ft by 2 ft or larger), or may be of different sizes, asdesired. For example, as seen in FIG. 1A, an alternative luminaire 30-1may have one large luminaire portion 32 a-1 of a size of about 2 ft by 2ft, a medium luminaire portion 32 b-1 of a size of about 1 ft by 1 ft,and four small luminaire portions 32 c-1 through 32 c-4 each of a sizeof about 6 in by 6 in, wherein the luminaire portions 32 are maintainedin assembled relation by a frame 34 comprising frame members 36 a-1through 36 a-4 and 36 b-1 through 36 b-5. (The luminaire portion sizesnoted above are approximate in the sense that the frame dimensions arenot taken into account.) Any other overall luminaire size and/or shapeand/or combinations of luminaire portion size(s), number(s), andrelative placement are possible.

As seen in FIG. 2 , each luminaire portion 32 includes a base element inthe form of a substrate 52 having a base surface 56. If desired, thebase surface 56 may be covered or coated by a reflective material, whichmay be a white material or a material that exhibits specular reflectivecharacteristics. A light source 60 that may include one or more lightemitting diodes (LEDs) is mounted on the base surface 56. The lightsource 60 may be one or more white or other color LEDs or may comprisemultiple LEDs either mounted separately or together on a singlesubstrate or package including a phosphor-coated LED either alone or incombination with at least one color LED, such as a green LED, a yellowor amber LED, a red LED, etc. In those cases where a soft whiteillumination is to be produced, the light source 60 typically includesone or more blue shifted yellow LEDs and one or more red LEDs. Differentcolor temperatures and appearances could be produced using other LEDcombinations, as is known in the art. In one embodiment, the lightsource comprises any LED, for example, an MT-G LED element incorporatingTrueWhite® LED technology or as disclosed in U.S. patent applicationSer. No. 13/649,067, filed Oct. 10, 2012, entitled “LED Package withMultiple Element Light Source and Encapsulant Having Planar Surfaces” byLowes et al., (Cree docket no. P1912US1-7), the disclosure of which ishereby incorporated by reference herein, both as developed by Cree,Inc., the assignee of the present application. In any of the embodimentsdisclosed herein the LED(s) have a particular emission distribution, asnecessary or desirable. For example, a side emitting LED disclosed inU.S. Pat. No. 8,541,795, the disclosure of which is incorporated byreference herein, may be utilized inside the waveguide body. Moregenerally, any lambertian, symmetric, wide angle, preferential-sided, orasymmetric beam pattern LED(s) may be used as the light source.

The light source 60 is operated by control circuitry (not shown) in theform of a driver circuit that receives AC or DC power. The controlcircuitry may be disposed on the substrate 52 or may be locatedremotely, or a portion of the control circuitry may be disposed on thesubstrate and the remainder of the control circuitry may be remotelylocated. In any event, the control circuitry is designed to operate thelight source 60 with AC or DC power in a desired fashion to producelight of a desired intensity and appearance. If necessary or desirable,a heat exchanger (not shown) is arranged to dissipate heat and eliminatethermal crosstalk between the LEDs and the control circuitry.Preferably, the light source 60 develops light appropriate for generalillumination purposes including light similar or identical to thatprovided by an incandescent, halogen, or other lamp that may beincorporated in a down light, a light that produces a wall washingeffect, a task light, a troffer, or the like.

A waveguide 70 has a main body of material 71 (FIG. 2 ), which, in theillustrated embodiment, has a width and length substantially greaterthan an overall thickness d thereof and, in the illustrated embodiment,is substantially or completely rectangular or any other shape in adimension transverse to the width and thickness (FIG. 1 ). Preferably,the thickness d may be at least about 500 microns, and more preferablyis between about 500 microns and about 10 mm, and is most preferablybetween about 3 mm and about 5 mm. The waveguide body 71 may be made ofany suitable optical grade material including one or more of acrylic,air, molded silicone, polycarbonate, glass, and/or cyclic olefincopolymers, and combinations thereof, particularly (although notnecessarily) in a layered arrangement to achieve a desired effect and/orappearance.

In the illustrated embodiment, the waveguide body 71 has a constantthickness over the width and length thereof, although the body 71 may betapered linearly or otherwise over the length and/or width such that thewaveguide body 71 is thinner at one or more edges than at a centralportion thereof. The waveguide body 71 further includes a first or outerside or surface 71 a, a second opposite inner side or surface 71 b, andan interior coupling cavity 76. The interior coupling cavity 76 isdefined by a surface 77 that, in the illustrated embodiment, extendspartially or fully through the waveguide 70 from the first side towardthe second side. Also in some of the illustrated embodiments, thesurface 77 defining the cavity 76 is preferably (although notnecessarily) normal to the first and second sides 71 a, 71 b of thewaveguide 70 and the cavity 76 is preferably, although not necessarily,centrally located with an outer surface of the main body of material 71.In some or all of the embodiments disclosed herein, the surface 77 (and,optionally, the surfaces defining alternate cavities described herein)is preferably polished and optically smooth. Also preferably, the lightsource 60 extends into the cavity 76 from the first side thereof. Stillfurther in the illustrated embodiment, a light diverter of any suitableshape and design, such as a conical plug member 78, extends into thecavity 76 from the second side thereof. Referring to FIGS. 2-4 , in afirst embodiment, the surface 77 is circular cylindrical in shape andthe conical plug member 78 includes a first portion 80 that conforms atleast substantially, if not completely, to the surface 77 (i.e., thefirst portion 80 is also circular cylindrical in shape) and the firstportion 80 is secured by any suitable means, such as, an interference orpress fit or an adhesive, to the surface 77 such that a second orconical portion 82 of the plug member 78 extends into the cavity 76.Preferably, although not necessarily, the conformance of the outersurface of the first portion 80 to the surface 77 is such that nosubstantial gaps exist between the two surfaces where the surfaces arecoextensive. Still further, if desired, the conical plug member 78 maybe integral with the waveguide body 71 rather than being separatetherefrom. Further, the light source 60 may be integral with or encasedwithin the waveguide body 71, if desired. In the illustrated embodiment,the first portion 80 preferably has a diameter of at least 500 um, andmore preferably between about 1 mm and about 20 mm, and most preferablyabout 3 mm. Further in the illustrated embodiment, the first portion 80has a height normal to the diameter of at least about 100 um, and morepreferably between about 500 um and about 5 mm, and most preferablyabout 1 mm. Still further in the illustrated embodiment, the secondportion 82 forms an angle relative to the portion 80 of at least about 0degrees, and more preferably between about 15 degrees and about 60degrees, and most preferably about 20 degrees. The plug member 78 may bemade of white polycarbonate or any other suitable transparent ortranslucent material, such as acrylic, molded silicone,polytetrafluoroethylene (PTFE), Delrin® acetyl resin, or any othersuitable material. The material of the plug member 78 may be the same asor different than the material of the waveguide body 71.

In all of the embodiments disclosed herein, one or more pluralities oflight extraction features or elements 88 may be associated with thewaveguide body 71. For example one or more light extraction features 88may be disposed in one or both sides or faces 71 a, 71 b of thewaveguide body 71. Each light extraction feature 88 comprises awedge-shaped facet or other planar or non-planar feature (e.g., a curvedsurface such as a hemisphere) that is formed by any suitable process,such as embossing, cold rolling, or the like, as disclosed in U.S.patent application Ser. No. 13/842,521. Preferably, in all of theembodiments disclosed herein the extraction features are disposed in anarray such that the extraction features 88 are disposed at a firstdensity proximate the cavity and gradually increase in density or sizewith distance from the light source 60, as seen in U.S. patentapplication Ser. No. 13/842,521. In any of the embodiments disclosedherein, as seen in FIGS. 3A and 3B, the extraction features may besimilar or identical to one another in shape, size, and/or pitch (i.e.,the spacing may be regular or irregular), or may be different from oneanother in any one or more of these parameters, as desired. The featuresmay comprise indents, depressions, or holes extending into thewaveguide, or bumps or facets or steps that rise above the surface ofthe waveguide, or a combination of both bumps and depressions. Featuresof the same size may be used, with the density of features increasingwith distance from the source, or the density of features may beconstant, with the size of the feature increasing with distance from thesource and coupling cavity. For example, where the density of theextraction features is constant with the spacing between features ofabout 500 microns, and each extraction feature comprises a hemisphere,the diameter of the hemisphere may be no greater than about 1 mm, morepreferably no greater than about 750 microns, and most preferably nogreater than about 100 microns. Where each extraction feature comprisesa shape other than a hemisphere, preferably the greatest dimension(i.e., the overall dimension) of each feature does not exceed about 1mm, and more preferably does not exceed about 750 microns, and mostpreferably does not exceed about 100 microns. Also, the waveguide body71 may have a uniform or non-uniform thickness. Irrespective of whetherthe thickness of the waveguide body 71 is uniform or non-uniform, aratio of extraction feature depth to waveguide body thickness ispreferably between about 1:10,000 and about 1:2, with ratios betweenabout 1:10,000 and about 1:10 being more preferred, and ratios betweenabout 1:1000 and about 1:5 being most preferred.

It should also be noted that the extraction features may be of differingsize, shape, and/or spacing over the surface(s) of the waveguide body sothat an asymmetric emitted light distribution is obtained. For example,FIG. 3C illustrates an arrangement wherein a relatively large number ofextraction features 88 a are disposed to the left of the coupling cavity76 and a relatively small number of extraction features 88 b aredisposed to the right of the coupling cavity 76. As should be evident,more light is extracted from the left side of the waveguide body 71 andrelatively less light is extracted from the right side of the waveguidebody 71.

In all of the embodiments disclosed herein, the waveguide body may becurved, thereby obviating the need for some or all of the extractionfeatures. Further, a diffuser 90 (FIG. 2 ) is preferably (although notnecessarily) disposed adjacent the side 71 a of the waveguide body 71and is retained in position by any suitable means (not shown).

In the first embodiment, and, optionally, in other embodiments disclosedherein, the second portion 82 of the plug member 78 is coated with areflecting material using any suitable application methodology, such asa vapor deposition process. Preferably, a thin reflective layer, such asa metal layer of particles, of appropriate layer thickness is uniformlydisposed on the conical portion 82 to allow sufficient light to transmitthrough the plug member 78 so that development of a visually observablespot (either too bright or too dark or color shifted with respect tosurrounding regions) is minimized at an outer surface of the diffuser 90adjacent the plug member 78. In the preferred embodiment the metal layercomprises aluminum or silver. In the case of silver, the reflectivelayer preferably has a thickness of no greater than about 100 nm, andmore preferably has a thickness between about 10 nm and about 70 nm, andmost preferably has a thickness of about 50 nm. In the case of aluminum,the reflective layer preferably has a thickness of no greater than about100 nm, and more preferably has a thickness between about 10 nm andabout 50 nm, and most preferably has a thickness of about 30 nm.

In any of the embodiments disclosed herein the second portion 82 of theplug member 78 may be non-conical and may have a substantially flatshape, a segmented shape, a tapered shape, an inclined shape to directlight out a particular side of the waveguide body 71, etc.

In alternate embodiments, as seen in FIGS. 6-16 , the plug member 78 hasa first portion of any other suitable noncircular shape, including asymmetric or asymmetric shape, as desired, and a second portionpreferably (although not necessarily) of conical shape as noted above.The coupling cavity may also (although it need not) have a noncircularshape or the shape may be circular where the first portion 80 isdisposed and secured (in which case the first portion 80 is circularcylindrical) and the shape of the coupling cavity may be noncircular inother portions (i.e., at locations remote from the first portion 80).

Specifically referring to FIGS. 6 and 7 , a first alternative cavity 100is illustrated in a waveguide body 71 wherein the cavity 100 is definedby four surfaces 102 a-102 d. Preferably, the four surfaces 102 arenormal to the upper and lower sides 71 a, 71 b and together define aquadrilateral shape, most preferably, a square shape in elevation asseen in FIG. 6 . Each of the surfaces 102 preferably has a side-to-sideextent (as seen in FIG. 6 ) of no less than about 500 um, and morepreferably between about 1 mm and 20 mm, depending upon the size of theLED element. The LED light source 60 is disposed in the cavity 100,similar or identical to the embodiment of FIG. 3 . A plug member 104includes a first portion 106 that conforms at least substantially, ifnot fully, as described in connection with the embodiment of FIG. 3 , tothe preferably square shape defined by the surfaces 102. Each of thesurfaces defining the first portion 106 has a height of no less thanabout 100 um, and more preferably between about 500 um and 5 mm, andmost preferably about 1 mm. The plug member 104 further includes aconical second portion 108 similar or identical to the portion 82 ofFIG. 3 both in shape and dimensions. The plug member 104 is otherwiseidentical to the plug member 78 and, in all of the embodiments disclosedin FIGS. 6-18 , the second portion 108 may be coated with the metallayer as described in connection with the plug member 78. The firstportion 106 is disposed and retained within the cavity 100 in anysuitable manner or may be integral therewith such that the secondportion 108 is disposed in the cavity 100 facing the light source 60, asin the embodiment of FIG. 3 . Preferably, the surfaces 102 are disposedat 45 degree angles with respect to edges or sides 114 a, 114 b, 114 c,and 114 d, respectively, of an LED element 114 comprising the lightsource 60. Referring to FIG. 5 , the illustrated LED element 114comprises six blue-shifted yellow LEDs 118 a-118 f disposed in two rowsof three LEDs located adjacent the edges or sides 114 a, 114 c. Threered LEDs 120 a-120 c are disposed in a single row between the two rowsof blue-shifted LEDs 118. (The embodiments of FIGS. 6-18 are illustratedwith the LED 114 element disposed in the same orientation as thatillustrated in FIG. 6 ). The light from the LEDs 118 and 120 is mixed bythe interaction of the light rays with the index of refraction interfaceat the surfaces 102 so that the ability to discern separate lightsources is minimized.

FIGS. 8-10 illustrate embodiments wherein a star-shaped cavity 130 isformed in the waveguide body 71 and a star shaped plug member 132 isretained within the star shaped cavity. Thus, for example, FIG. 8 astar-shaped cavity 130-1 having eight equally spaced points 130 a-130 his formed in the waveguide body 71 such that points 130 a, 130 c, 130 e,and 130 g are aligned with the sides 114 a, 114 b, 114 c, and 114 d,respectively, of the LED element 114. FIG. 10 illustrates a cavity 130-2identical to the cavity 130-1 of FIG. 8 except that the cavity 130-2 isrotated 22.5 degrees counter-clockwise relative to the cavity 130-1. Inboth of the embodiments of FIGS. 8-10 the plug member 132 includes afirst portion 134 that substantially or completely conforms to the wallsdefining the cavity 130. In this embodiment, the cavity 130 and plugmember 132 have sharp points.

FIGS. 11-13 illustrate embodiments identical to FIGS. 8-10 with theexception that eight-pointed cavities 150-1 and 150-2 and plug member152 have rounded or filleted points. Preferably, each fillet has aradius of curvature between about 0.1 mm and about 0.4 mm, and morepreferably has a radius of curvature between about 0.2 mm and 0.3 mm,and most preferably has a radius of curvature of about 0.25 mm.

Of course, any of the embodiments disclosed herein may have a differentnumber of points, whether sharp pointed or rounded, or a combination ofthe two. FIGS. 14-16 illustrate embodiments of cavities 170, 190 (andcorresponding first portions of associated plug members) havingrelatively large numbers of points (16 points in FIG. 14 , 32 points inFIGS. 15 and 16 ) of different shapes and sizes. In these alternativeembodiments, the star shaped coupling cavity includes a first pluralityof points 172 (FIG. 14 ) and a second plurality of points 174, and thefirst plurality of points 172 have a different shape than the secondplurality of points 174. Thus, the coupling cavity is defined by a firstset of surfaces 176 a-176 d (defining the first plurality of points 172)that direct a first distribution of light into the waveguide body and asecond set of surfaces 178 a-178 d (defining the second plurality ofpoints 174) that direct a second distribution of light different thanthe first distribution of light into the waveguide body. In theseembodiments, the angles of the surfaces with respect to the central axisimpact the luminance uniformity and color mixing of the light emittedfrom the light source. In particular, light uniformity and color mixingimprove as the angled surface(s) of the coupling cavity becomeincreasingly parallel with light rays (within Fresnel scattering angularlimits, as should be evident to one of ordinary skill in the art), thusmaximizing the angle of refraction, and hence light redirection, as therays traverse the interface between the low index of refraction medium(air) and the higher index of refraction medium (the waveguide). Whilelight uniformity and color mixing may be enhanced using complex shapes,such benefit must be weighed against the difficulty of producing suchshapes.

In each of the embodiments of FIGS. 8, 10, 11 and 13-16 , each cavitymay have radially maximum size (i.e., the distance between a center orcentroid (in the case of noncircular coupling cavity shapes) of thecavity and an outermost portion of the surface(s) defining the cavity)of at least about 100 um, and more preferably between about 1 mm and nomore than about 50 mm, and most preferably between about 3 mm and about20 mm. Further, each cavity may have radially minimum size (i.e., thedistance between a center or centroid of the cavity and an innermostportion of the surface(s) defining the cavity) of at least about 100 um,and more preferably between about 1 mm and about 50 mm, and mostpreferably between about 3 mm and about 20 mm. (The term “centroid” asused herein is defined as the center of gravity of an imaginary mass ofconstant thickness and uniform density fully occupying the couplingcavity.)

The first and second portions of the plug members of FIGS. 9 and 12 (andplug members that may be used with FIGS. 14 and 15 ) may be identical tothe plug members described previously, with the exception of the outsideshape of the first portion, as should be evident.

Ray fan and full simulation analyses of the embodiments shown in FIGS.6-16 were performed to compare color mixing, luminance, and efficiencyof waveguides having various shapes of coupling cavities with the designshown in FIGS. 2-4 . Ray fan simulations of LED elements withinvarious-shaped coupling cavities demonstrated the color mixing of lightrays emitted horizontally from the LED into the waveguide. Fullsimulations of LED elements within various shaped coupling cavitiesdemonstrated the color mixing, luminance, and efficiency of light raysemitted from the LED into the waveguide having extraction features.LightTools 8.0 by Synopsys was utilized to perform the simulations,although other software known in the art, such as Optis by Optis orRadiant Zemax by Zemax, may be used.

It should be noted that the coupling cavity may have an asymmetricshape, if desired. FIG. 16A illustrates a triangular coupling cavity 179defined by three coupling features 179 a-179 c that extend at leastpartially between upper and lower surfaces of a waveguide body 180. Thecavity 179 has an asymmetric triangular shape with respect to a centroid181. Although not shown, one or more LEDs and a light diverter extendinto the coupling cavity 179 as in the other embodiments disclosedherein.

In embodiments disclosed herein, a coupling cavity is defined by one ormore coupling features that extend between the first and second faceswherein at least one of the coupling features extends into the waveguidebody to a lateral extent transverse to a depth dimension greater than alateral extent to which another of the waveguide features extends intothe waveguide body. Thus, for example, as seen in FIG. 16A, the couplingfeature 179 a includes at least one portion 179 a-1 that is disposed toa greater extent farther into the waveguide body 180 than portions 179c-1 and 179 c-2 of the feature 179 c. The same is true of otherembodiments. Further, where the coupling surfaces do not extend fullythrough the waveguide body, the resulting blind cavity may have one ormore shaped cavity base surface(s) or a planar cavity base surface andthe cavity base surface(s) may (but need not) be coated with areflective and/or partially light transmissive material, if desired.

Referring next to FIGS. 17 and 18 , the placement of LEDs on thesubstrate can be modified to enhance color mixing. FIG. 17 illustratesan embodiment in which the red LEDs 120 are reduced in number to twoLEDs 120 a, 120 b. FIG. 18 illustrates an embodiment wherein the blueshifted yellow LEDs 118 comprise first and second single LEDs 118 a, 118c disposed adjacent the edges or sides 114 a, 114 c and first and secondpairs of LEDs 118 b 1, 118 b 2 and 118 d 1, 118 d 2, adjacent the sides114 b, 114 d, respectively. Two red LEDs 120 a, 120 b are disposedbetween the LEDs 118 remote from the edges or sides 114. FIG. 18Aillustrates an embodiment in which the LEDs 118, 120 are disposed in acheckerboard pattern with the red LEDs 120 being disposed between theblue-shifted LEDs 118.

In addition to the foregoing, the shape or other characteristic of anyoptics in the path of light may be varied. More particularly, a modifiedprimary or secondary lens 192 (FIG. 32 ) may be used in conjunction withthe LED light source 60 to further improve the luminance and/or coloruniformity of the light emitted from the surface of the waveguide. Inany embodiment, the primary LED light source lens may be varied andoptimized to use refraction or scattering to direct light into preferreddirections prior to entering the coupling cavity, thereby improvinguniformity. The orientation and/or shape of the LED element relative tothe surface(s) defining the coupling cavity may also be varied andoptimized to improve light mixing. The lens 192 and/or any of thewaveguides disclosed herein may be formed with one or more materials inaccordance with the teachings of either U.S. patent application Ser. No.13/843,928, filed Mar. 15, 2013, entitled “Multi-Layer Polymeric Lensand Unitary Optic Member for LED Light Fixtures and Method ofManufacture” by Craig Raleigh et al., (Cree docket no. P1988US1), orU.S. patent application Ser. No. 13/843,649, filed Mar. 15, 2013,entitled “One-Piece Multi-Lens Optical Member and Method of Manufacture”by Craig Raleigh et al., (Cree docket no. P2026US1), the disclosures ofwhich are hereby incorporated by reference herein. If desired, ascatterer, which may be effectuated by scattering particles coated on orformed within the lens 192, may be provided to further mix the lightdeveloped by the LEDs.

Non-uniform illuminance by the luminaire 30 may be addressed by securinga masking element 210 to the diffuser 90 to obscure bright spots, asseen in FIGS. 19 and 20 . The masking element 210 may have any desiredshape, may comprise single or multiple sub-elements, and/or may betranslucent or opaque. The masking element may be made of any desiredmaterial, and should minimize the absorption of light.

In the illustrated embodiment, the light emitted out the waveguide bodyis mixed such that point sources of light in the source 60 are notvisible to a significant extent and the emitted light is controlled to ahigh degree. The interface between the coupling cavity and the waveguideas described above also results in obscuring discrete point sources.

Further, it may be desirable to redirect light within the waveguide toprovide better luminance uniformity from discrete light sources, and/orto provide mixing of colors from multi-color sources. In addition to anyor all of the features and embodiments disclosed herein, a waveguide mayinclude internal redirection features that implement scattering,reflection, TIR, and/or refraction to redirect the light within thewaveguide body. The spacing, number, size and geometry of redirectionfeatures determine the mixing and distribution of light within thewaveguide. In some circumstances, the redirection feature may bedesigned such that some of the light is directed out of, i.e. extractedfrom, the waveguide body as well.

In one embodiment, the waveguide may include one or more extractionfeatures on the one or more external faces to direct light out of thebody, and one or more internal redirection features to redirect lightwithin the body. In general, light reflected off of the extractionfeatures travels relatively directly to the external surface, whereaslight reflected off of the redirection features travels some distancewithin the waveguide before exiting through the external surface. Suchredirection within the body of the waveguide is referred to hereinafteras occurring “in-plane.” In-plane redirection causes the light ray to beextracted from the waveguide at a modified, laterally-displacedextraction point, in contrast to the original or unaltered extractionpoint at which the light ray would have otherwise been extracted. Themodified extraction point is preferred to the unaltered extraction pointas the in-plane redirection enhances color uniformity within the body.

Referring to FIG. 21 , a waveguide 250 may comprise a body 252exhibiting a total internal reflectance characteristic and having afirst external face 254 and a second external face 256 opposite thefirst external face 254. One or more coupling cavities or recesses 258extends between and is preferably (although not necessarily) fullydisposed between the first and second external faces 254, 256, and isadapted to receive a light source 259 (shown in FIG. 27 ). As inprevious embodiments the light source 259 may include one or more LEDsthat are configured to direct light into the waveguide body 252. A plugmember (as in the previous embodiments, not shown in FIG. 21 ) may beused to direct light emitted by the LED(s) into the waveguide body 252.The waveguide body 252 also includes one or more redirection features260 a, 260 b, 260 c, 260 d configured to redirect light emitted from theLED(s) in-plane.

As shown in FIG. 22 , the redirection feature 260 is preferably at leastpartially or fully internal to the waveguide body 252 and comprisessurfaces defining two opposing arcuate voids 261-1, 261-2 extendingalong the planar direction. The redirection feature 260 preferably,although not necessarily, has a substantially constant thickness (i.e.,depth) of about 1 mm and either or both of the voids 261 may be filledwith air, acrylic, an acrylic material including scattering particles,polycarbonate, glass, molded silicone, a cyclic olefin copolymer, oranother material having an index of refraction different than or thesame as the index of refraction of the remainder of the waveguide body252, or combinations thereof.

Shown most clearly in FIG. 23 , the body 252 is comprised of a firstplate 262 and a second plate 264 bonded or otherwise secured to oneanother, wherein the first and second plates 262, 264 include the firstand second external faces 254, 256, respectively. The coupling cavity258 is formed in and extends into at least one of the first and secondplates 262, 264 and may comprise any fraction of the thickness of thewaveguide body from about 1% or less to 100% of such thickness. Thefirst and second plates 262, 264 are optically transmissive bodies, andmay be made of the same or different materials. Both of the first andsecond plates 262, 264 exhibit a total internal reflectioncharacteristic. The first plate 262 includes a first internal face 266opposite the first external face 254, and the second plate 264 includesa second internal face 268 opposite the second external face 256. Thesecond internal face 268 of the second plate 264 is maintained incontact with the first internal face 266 of the first plate 262. In theillustrated embodiment the redirection feature 260 is formed by anysuitable manufacturing process extending into the first plate 262 fromthe first internal face 266. Alternatively, in any of the embodimentsdisclosed herein, the redirection feature 260 may extend into the secondplate 264 from the second internal face 268 or portions of theredirection feature 260 may extend into both plates 262, 264 from thefaces 266, 268, as should be evident. In this last case, the portions ofthe redirection feature 260 may be partially or fully aligned with oneanother, as necessary or desirable.

FIGS. 24 and 25 illustrate an embodiment wherein the waveguide body 252includes first alternative redirection features 272 each having atriangular cross-sectional shape associated with the first plate 262.Further, the waveguide body 252 may include one or more extractionfeatures 274 on the first and second external faces 254, 256 to directlight out of the body 252. The internal redirection features 272 mayalso extract light out of the waveguide body 252 as well. A furtherredirection feature 278 may be embossed or otherwise associated with thesecond internal face 268 of the second plate 264.

Referring to FIG. 26 , the redirection feature 272 is embossed, molded,screen printed, machined, laser-formed, laminated, or otherwise formedand disposed on the first internal face 266 of the first plate 262, andthe first internal face 266 of the first plate 262 is thereafter securedto the second internal face 268 of the second plate 264. In any of theembodiments such securement may be accomplished by applying a solvent toone of the internal faces that chemically reacts with the waveguide bodymaterial to promote adhesion, and then pressing the internal facestogether. Alternatively, the surfaces may be bonded through theapplication of high pressure and heat, or an adhesive material may bedisposed between the surfaces. Other fabrication methods, such asthrough the use of a three-dimensional printer, are envisioned. Stillfurther, other structures are within the scope of the present invention,including a film or other member having a portion having a first indexof refraction and formed by any suitable methodology, such as thosenoted above (embossing, molding, screen printing, etc.), and sandwichedbetween two members both having a second index of refraction differentthan the first index of refraction. A further alternative comprehends afilm or other structure disposed between two other members, wherein thefilm or other structure has a first index of refraction, a first of thetwo members has a second index of refraction and the other of the twomembers has a third index of refraction wherein the first, second, andthird indices of refraction are different or where the film or otherstructure comprises an index-matching material.

As shown in FIG. 27 , second and third alternative redirection features282, 284 may extend from the coupling cavity 258 in a radial direction.Second alternative redirection features 282 have a rectangular shape,and third alternative redirection features 284 have a V-shape in planview. It has been found that radially-extending redirection features areespecially useful in promoting mixing of light emitted by an LED elementhaving multiple LEDs distributed in spaced relation on a substrate suchthat at least some of the LEDs are disposed off-axis, i.e., such LEDsare offset from the center of the cavity in which the LED element isdisposed. Specifically, light rays 280 emitted from the LEDs arereflected off of the redirection features 282, 284 due, for example, tototal internal reflection, in different directions within the waveguidebody 252.

One or more other light redirection feature shapes could be used, suchas circular, diamond-shaped (seen in FIG. 28A), kite-shaped (i.e., adiamond shape with different angles at opposing ends of the shape),rectangular, polygonal, curved, flat, tapered, segmented, continuous,discontinuous, symmetric, asymmetric, etc. The light redirection featurepreferably has an overall radial length of no less than about 1 um, andmore preferably the overall radial length is between about 10 um andabout 10 mm, and most preferably between about 1 mm and about 10 mm.Further the light redirection feature preferably has an overallcircumferential extent of no less than about 1 um, and more preferablythe overall circumferential extent is between about 10 um and about 10mm, and most preferably between about 1 mm and about 10 mm. Any or allof the surfaces partially or fully defining any or all of the featuresdisclosed herein, including the light redirection features disclosedherein, or any portion thereof, may be coated or otherwise formed withoptically reflective materials, such as a specular material, such as ametallized coating, a scattering material, a white material, or thelike, if desired.

It should be noted that the number, size, and arrangement of the lightredirection features may be such as to gradually collimate light overthe extent of the waveguide body and/or could cause redirection of lightfor another purpose, for example, to cause the light to avoid featuresthat would otherwise absorb or scatter such light.

As seen in FIG. 31 , a waveguide body 360 includes a coupling cavity 362defined by a surface 364 and an LED element 366 extends into the cavity362. In an illustrated embodiment, the cavity 362 does not extend fullythrough the waveguide body 360, and instead comprises a blind bore thatterminates at a planar base surface 370 that comprises a light diverter.It should be noted that the surface 364 need not be circular cylindricalin shape as seen in FIG. 31 ; rather, the surface 364 may comprise aplurality of light coupling features in the form of facets or othershaped surfaces. In addition, the planar base surface 370 may also bereplaced by other shaped surfaces, such as a conical surface (eitherconvex or concave) or planar, segmented sections that taper to a pointcoincident with a central axis of the cavity 362. This embodiment isparticularly adapted for use with relatively thin waveguide bodies.Also, the planar base surface 370 may be coated with a reflectivematerial, such as a white or specular material as noted above withrespect to the plug member.

Still further, the surface 364 (and/or any of the embodiments disclosedherein) may comprise an elongate light coupling cavity or portion, i.e.,a cavity or portion that is not fully circular cylindrical, but at leasta portion of the cavity or portion is instead another shape, such aselliptical, oval, racetrack-shaped, teardrop-shaped, symmetric orasymmetric, continuous or segmented, etc.

FIGS. 28 and 28A illustrate generally that the LED light source 259 neednot be located at one or more interior portions of a waveguide body(such an arrangement can be referred to as an interior lit waveguide),it being understood that, as shown, the LED light source 259 may beadjacent or in an edge 302 of the waveguide body to obtain either anedge lit waveguide or an end lit waveguide, as described below. In edgelit embodiments, the light source 259 may be above, below, and/or to theside of the edge 302 and aligned therewith (as seen in FIG. 28 ). Thewaveguide body preferably includes at least one coupling feature 305(FIG. 28A) defining a coupling cavity 309, and, if desirable, at leastone redirection feature 307 (also seen in FIG. 28A) extending away fromthe coupling cavity 309 and the LED light source 259 as disclosed in theprevious embodiments. A reflecting cover or member 303 may be disposedover, under or otherwise adjacent to the light source 259 in any of theembodiments disclosed herein, including the embodiment of FIG. 28 , ifdesired.

A combined interior lit and edge lit waveguide (also referred to as anend lit waveguide) may be obtained by providing coupling features atinterior portions and edge(s) of the waveguide. Specifically, FIGS. 29and 30 illustrate an embodiment in which one or more light sources 259are disposed adjacent an elongate coupling section or portion 310 of acoupling optic 312. The coupling section 310 includes at least onecoupling feature and, if desired, at least one redirection feature as inthe embodiments described above.

Referring next to FIG. 33 , an alternate noncircular coupling cavity 400is formed by any suitable methodology in any of the waveguide bodiesdisclosed herein (the coupling cavity 400 is noncircular in the sensethat the surfaces defining the cavity 400, at least where light entersthe waveguide body, do not define a smooth circle). The coupling cavity400, which may comprise a blind cavity or a cavity that extends fullythrough the waveguide body, includes one or more coupling features inthe form of a circumferential array of inwardly directed surfaces, shownas bumps or protrusions 402. The bumps or protrusions 402, each of whichmay comprise curved, planar, and/or other-shaped surfaces, promotemixing of light by providing surfaces at varying angles with respect toincident light rays developed by an LED light source 114. In the eventthat the coupling cavity extends fully through the waveguide body, alight diverter (not shown) may be provided opposite the LED light source114, as in previous embodiments.

FIGS. 34 and 35 illustrate an embodiment identical to that shown in FIG.33 , except that the single circumferential array of inwardly directedcurved surfaces are replaced by one or more coupling features comprisingfirst and second circumferential arrays of surfaces comprising bumps orprotrusions generally indicated at 410, 412. As seen in FIG. 35 , thefirst array of bumps or protrusions 410 is axially shorter than thesecond array of bumps or protrusions 412. Further, the first array ofbumps or protrusions 410 is disposed radially inside the second array ofbumps or protrusions 412 and is coaxial therewith. Light developed by anLED light source 114 is efficiently mixed by the arrays 410, 412.

In any of the embodiments disclosed herein, gaps or interfaces betweenwaveguide elements may be filled with an optical coupling gel or adifferent optical element or material, such as an air gap.

INDUSTRIAL APPLICABILITY

In summary, it has been found that when using a single color ormulticolor LED element in a luminaire, it is desirable to mix the lightoutput developed by the LEDs thoroughly so that the intensity and/orcolor appearance emitted by the luminaire is uniform. When the LEDelement is used with a waveguide, opportunities have been found to existto accomplish such mixing during the light coupling and light guiding ordistributing functions. Specifically, bending the light rays byrefraction can result in improvement in mixing. In such a case, thisrefractive bending can be accomplished by providing interfaces in thewaveguide between materials having different indices of refraction.These interfaces may define coupling features where light developed bythe LED elements enters the waveguide and/or light redirection featuresat portions intermediate the coupling features and waveguide extractionfeatures or areas where light is otherwise extracted (such as by bends)from the waveguide. It has further been found that directing light intoa wide range of refraction angles enhances light mixing. Because theangle A_(r) of a refracted light ray is a function of the angle A_(i)between the incident light ray and the interface surface struck by theincident light ray (with refractive angle A_(r) increasing as A_(i)approaches zero, i.e., when the incident light ray approaches a parallelcondition with respect to the interface surface), a wide range ofrefracted light ray angles can be obtained by configuring the interfacesurfaces to include a wide range of angles relative to the incidentlight rays. This, in turn, means that the interfaces could include asignificant extent of interface surfaces that are nearly parallel to theincident light rays, as well as other surfaces disposed at other anglesto the incident light rays. Overall waveguide shapes and couplingfeature and redirection feature shapes such as curved (including convex,concave, and combinations of convex and concave surfaces), planar,non-planar, tapered, segmented, continuous or discontinuous surfaces,regular or irregular shaped surfaces, symmetric or asymmetric shapes,etc. can be used, it being understood that, in general, light mixing(consistent with the necessary control over light extraction) can befurther improved by providing an increased number of interface surfacesand/or more complex interface shapes in the light path. Also, thespacing of coupling features and light redirection features affect thedegree of mixing. In some embodiments a single light coupling featureand/or a single light redirection feature may be sufficient toaccomplish a desired degree of light mixing. In other embodiments,multiple coupling features and/or multiple light redirection featuresmight be used to realize a desired degree of mixing. In either event,the shapes of multiple coupling features or multiple redirectionfeatures may be simple or complex, they may be the same shape or ofdifferent shapes, they may be equally or unequally spaced, ordistributed randomly or in one or more arrays (which may themselves beequally or unequally spaced, the same or different size and/or shape,etc.) Further, the interfaces may be disposed in a symmetric orasymmetric pattern in the waveguide, the waveguide itself may besymmetric or asymmetric, the waveguide may develop a light distributionthat is symmetric, asymmetric, centered or non-centered with respect tothe waveguide, the light distribution may be on-axis (i.e., normal to aface of the waveguide) or off-axis (i.e., other than normal with respectto the waveguide face), single or split-beam, etc.

Still further, one or more coupling features or redirection features, orboth, may be disposed anywhere inside the waveguide, at any outsidesurface of the waveguide, such as an edge surface or major face of thewaveguide, and/or at locations extending over more than one surface orportion of the waveguide. Where a coupling or light redirection featureis disposed inside the waveguide, the feature may be disposed in or bedefined by a cavity extending fully through the waveguide or in or by acavity that does not extend fully through the waveguide (e.g., in ablind bore or in a cavity fully enclosed by the material of thewaveguide). Also, the waveguide of any of the embodiments disclosedherein may be planar, non-planar, irregular-shaped, curved, othershapes, suspended, a lay-in or surface mount waveguide, etc.

While specific coupling feature and light redirection feature parametersincluding shapes, sizes, locations, orientations relative to a lightsource, materials, etc. are disclosed as embodiments herein, the presentinvention is not limited to the disclosed embodiments, inasmuch asvarious combinations and all permutations of such parameters are alsospecifically contemplated herein. Thus, any one of the couplingcavities, plug members, LED elements, masking element(s), redirectionfeatures, extraction features, etc. as described herein may be used in aluminaire, either alone or in combination with one or more additionalelements, or in varying combination(s) to obtain light mixing and/or adesired light output distribution. More specifically, any of thefeatures described and/or claimed in U.S. patent application Ser. No.13/842,521, U.S. patent application Ser. No. 13/839,949, U.S. patentapplication Ser. No. 13/841,074, filed Mar. 15, 2013, entitled “OpticalWaveguide Body”, U.S. patent application Ser. No. 13/840,563, U.S.patent application Ser. No. 14/101,086, filed Dec. 9, 2013, entitled“Optical Waveguides and Luminaires Incorporating Same”, U.S. patentapplication Ser. No. 14/101,099, filed Dec. 9, 2013, entitled “OpticalWaveguide Assembly and Light Engine Including Same”, U.S. patentapplication Ser. No. 14/101,132, filed Dec. 9, 2013, entitled “WaveguideBodies Including Redirection Features and Methods of Producing Same”,U.S. patent application Ser. No. 14/101,129, filed Dec. 9, 2013,entitled “Simplified Low Profile Module With Light Guide For Pendant,Surface Mount, Wall Mount and Stand Alone Luminaires”, and U.S. patentapplication Ser. No. 14/101,051, filed Dec. 9, 2013, entitled “OpticalWaveguide and Lamp Including Same”, incorporated by reference herein andowned by the assignee of the present application may be used in thedevices disclosed herein. Thus, for example, any of the waveguides orluminaires disclosed herein may include one or more coupling features,one or more light redirection features, one or more coupling features oroptics, a modified LED arrangement, one or more extraction features,and/or particular waveguide or overall luminaire shapes and/orconfigurations as disclosed in such applications, as necessary ordesirable. Other luminaire and waveguide form factors than thosedisclosed herein are also contemplated.

The coupling features disclosed herein efficiently couple light into thewaveguide, and the redirection features uniformly mix light within thewaveguide and the light is thus conditioned for uniform extraction outof the waveguide. At least some of the luminaires disclosed herein areparticularly adapted for use in installations, such as, replacement orretrofit lamps (e.g., LED PAR bulbs), outdoor products (e.g.,streetlights, high-bay lights, canopy lights), and indoor products(e.g., downlights, troffers, a lay-in or drop-in application, a surfacemount application onto a wall or ceiling, etc.) preferably requiring atotal luminaire output of at least about 800 lumens or greater, and,more preferably, a total luminaire output of at least about 3000 lumens,and most preferably a total lumen output of about 10,000 lumens.Further, the luminaires disclosed herein preferably have a colortemperature of between about 2500 degrees Kelvin and about 6200 degreesKelvin, and more preferably between about 2500 degrees Kelvin and about5000 degrees Kelvin, and most preferably about 2700 degrees Kelvin.Also, at least some of the luminaires disclosed herein preferablyexhibit an efficacy of at least about 100 lumens per watt, and morepreferably at least about 120 lumens per watt, and further exhibit acoupling efficiency of at least about 92 percent. Further, at least someof the luminaires disclosed herein preferably exhibit an overallefficiency (i.e., light extracted out of the waveguide divided by lightinjected into the waveguide) of at least about 85 percent. A colorrendition index (CRI) of at least about 80 is preferably attained by atleast some of the luminaires disclosed herein, with a CRI of at leastabout 88 being more preferable. A gamut area index (GAI) of at leastabout 65 is achievable as is a thermal loss of less than about 10%. Anydesired form factor and particular output light distribution, such as abutterfly light distribution, could be achieved, including up and downlight distributions or up only or down only distributions, etc.

When one uses a relatively small light source which emits into a broad(e.g., Lambertian) angular distribution (common for LED-based lightsources), the conservation of etendue, as generally understood in theart, requires an optical system having a large emission area to achievea narrow (collimated) angular light distribution. In the case ofparabolic reflectors, a large optic is thus generally required toachieve high levels of collimation. In order to achieve a large emissionarea in a more compact design, the prior art has relied on the use ofFresnel lenses, which utilize refractive optical surfaces to direct andcollimate the light. Fresnel lenses, however, are generally planar innature, and are therefore not well suited to re-directing high-anglelight emitted by the source, leading to a loss in optical efficiency. Incontrast, in the present invention, light is coupled into the optic,where primarily TIR is used for re-direction and collimation. Thiscoupling allows the full range of angular emission from the source,including high-angle light, to be re-directed and collimated, resultingin higher optical efficiency in a more compact form factor.

Embodiments disclosed herein are capable of complying with improvedoperational standards as compared to the prior art as follows:

State of the Improved Standards art standards Achievable by PresentEmbodiments Input coupling 90% About 95% plus improvements throughefficiency color mixing, source mixing, and (coupling + control withinthe waveguide waveguide) Output 90% About 95%: improved throughextraction efficiency efficiency plus controlled distribution(extraction) of light from the waveguide Total system ~80%  About 90%:great control, many choices of output distribution

In at least some of the present embodiments the distribution anddirection of light within the waveguide is better known, and hence,light is controlled and extracted in a more controlled fashion. Instandard optical waveguides, light bounces back and forth through thewaveguide. In the present embodiments, light is extracted as much aspossible over one pass through the waveguide to minimize losses.

In some embodiments, one may wish to control the light rays such that atleast some of the rays are collimated, but in the same or otherembodiments, one may also wish to control other or all of the light raysto increase the angular dispersion thereof so that such light is notcollimated. In some embodiments, one might wish to collimate to narrowranges, while in other cases, one might wish to undertake the opposite.

All references, including publications, patent applications, andpatents, cited herein are hereby incorporated by reference to the sameextent as if each reference were individually and specifically indicatedto be incorporated by reference and were set forth in its entiretyherein.

The use of the terms “a” and “an” and “the” and similar references inthe context of describing the invention (especially in the context ofthe following claims) are to be construed to cover both the singular andthe plural, unless otherwise indicated herein or clearly contradicted bycontext. Recitation of ranges of values herein are merely intended toserve as a shorthand method of referring individually to each separatevalue falling within the range, unless otherwise indicated herein, andeach separate value is incorporated into the specification as if it wereindividually recited herein. All methods described herein can beperformed in any suitable order unless otherwise indicated herein orotherwise clearly contradicted by context. The use of any and allexamples, or exemplary language (e.g., “such as”) provided herein, isintended merely to better illuminate the disclosure and does not pose alimitation on the scope of the disclosure unless otherwise claimed. Nolanguage in the specification should be construed as indicating anynon-claimed element as essential to the practice of the disclosure.

Numerous modifications to the present disclosure will be apparent tothose skilled in the art in view of the foregoing description. Preferredembodiments of this disclosure are described herein, including the bestmode known to the inventors for carrying out the disclosure. It shouldbe understood that the illustrated embodiments are exemplary only, andshould not be taken as limiting the scope of the disclosure.

We claim:
 1. A waveguide, comprising: a waveguide body having a widthand length that are substantially greater than a thickness thereof,where the thickness extends in a direction between a first side and asecond side, wherein the waveguide body comprises a first plate and asecond plate and wherein the first plate includes a first external facethat defines the first side and a first internal face and the secondplate includes a second external face that defines the second side and asecond internal face, the first internal face being in contact with thesecond internal face; a plurality of redirection features between thefirst plate and the second plate of the waveguide body; a couplingcavity comprising a coupling feature configured to couple light into thewaveguide body, wherein the coupling cavity is disposed within thewaveguide body and extends in the direction; and a plug member having afirst portion disposed in the coupling cavity and an outer surfacesubstantially conforming to the coupling feature and a second portionextending from the first portion into the coupling cavity wherein thesecond portion includes a reflective surface adapted to direct light inthe coupling cavity into the waveguide body.
 2. The waveguide of claim1, wherein the plurality of redirection features is formed on at leastone of the first internal face and the second internal face of thewaveguide body.
 3. The waveguide of claim 1, wherein the coupling cavityextends into the first plate and the second plate of the waveguide body.4. The waveguide of claim 1, wherein the outer surface of the plugmember has one of a cylindrical shape, a star shape, and a quadrilateralshape.
 5. The waveguide of claim 4, wherein the star shape comprisesequally spaced points.
 6. The waveguide of claim 1, wherein thewaveguide body includes a plurality of light extraction features.
 7. Thewaveguide of claim 1, wherein the second portion of the plug member isconical in shape.
 8. The waveguide of claim 1, further comprising adiffuser at least partially covering one of the first side and thesecond side of the waveguide body.
 9. The waveguide of claim 8, furthercomprising a masking element partially covering the diffuser to obscurebright spots.
 10. A waveguide, comprising: a waveguide body having awidth and length that are substantially greater than a thicknessthereof, where the thickness extends in a direction between a first sideand a second side, wherein the waveguide body comprises a first plateand a second plate and wherein the first plate includes a first externalface that defines the first side and a first internal face and thesecond plate includes a second external face that defines the secondside and a second internal face, the first internal face being incontact with the second internal face; a coupling cavity comprising acoupling feature configured to couple light into the waveguide body,wherein the coupling cavity is disposed within the waveguide body andextends in the direction; a plug member having a first portion disposedin the coupling cavity and an outer surface substantially conforming tothe coupling feature and a second portion extending from the firstportion into the coupling cavity wherein the second portion includes areflective surface adapted to direct light in the coupling cavity intothe waveguide body; and a redirection feature that extends into at leastone of the first internal face and the second internal face of thewaveguide body and extends radially from the coupling cavity.
 11. Thewaveguide of claim 10, wherein the redirection feature is at least oneof embossed, molded, screen printed, machined, laser-formed, andlaminated on at least one of the first internal face and the secondinternal face.
 12. The waveguide of claim 10, wherein the redirectionfeature is at least partially formed with an optically reflectivematerial.
 13. The waveguide of claim 12, wherein the opticallyreflective material comprises at least one of a metallized coating, ascattering material, and a white material.
 14. The waveguide of claim10, wherein the outer surface of the plug member has one of acylindrical shape, a star shape, and a quadrilateral shape.
 15. Thewaveguide of claim 14, wherein the star shape comprises equally spacedpoints.
 16. The waveguide of claim 10, wherein the waveguide bodyincludes a plurality of light extraction features.
 17. The waveguide ofclaim 10, wherein the second portion of the plug member is conical inshape.
 18. A waveguide, comprising: a waveguide body having a width andlength that are substantially greater than a thickness thereof, wherethe thickness extends in a direction between a first side and a secondside, wherein the waveguide body comprises a first plate and a secondplate and wherein the first plate includes a first external face thatdefines the first side and a first internal face and the second plateincludes a second external face that defines the second side and asecond internal face, the first internal face being in contact with thesecond internal face; a coupling cavity comprising a coupling featureconfigured to couple light into the waveguide body, wherein the couplingcavity is disposed within the waveguide body and extends in thedirection; a plug member having a first portion disposed in the couplingcavity and an outer surface substantially conforming to the couplingfeature and a second portion extending from the first portion into thecoupling cavity wherein the second portion includes a reflective surfaceadapted to direct light in the coupling cavity into the waveguide body;a diffuser at least partially covering one of the first side and thesecond side of the waveguide body; and a masking element partiallycovering the diffuser to obscure bright spots.
 19. The waveguide ofclaim 18, further comprising a plurality of redirection features betweenthe first plate and the second plate of the waveguide body, wherein theplurality of redirection features is formed on at least one of the firstinternal face and the second internal face of the waveguide body. 20.The waveguide of claim 18, wherein the coupling cavity extends into thefirst plate and the second plate of the waveguide body.